Feeder system with independent control of rollers

ABSTRACT

The present subject matter relates to a feed roller system for high speed image scanning equipment, which improves the feeding of documents, and in particular, thin or ultra-thin documents, into the scanner equipment. The feed roller system comprises a pick roller and a feed roller, each associated with its own clutch, allowing the pick roller and feed roller to be selectively driven together, independently, and/or not at all. Initially, both rollers are driven to feed a document. Drive to the pick roller is disabled by the pick roller clutch when the leading edge of the document reaches a gap control sensor, downstream of the rollers. Drive to the feed roller continues until it is disabled by the feed roller clutch when the leading edge of the document reaches a page entry sensor, downstream of the gap control sensor and the first transport rollers. The first transport rollers continue to feed the document, while the pick roller and the feed roller are disengaged, thus preventing overfeeding or misfeeding by the pick roller and/or feed roller.

TECHNICAL FIELD

The exemplary teachings herein pertain to methods and systems for scanning documents, and in particular, to a document feeder system for an imaging device such as a scanner, facsimile, or the like, characterized by the improved feeding of documents, especially short and thin documents, to high speed image scanning equipment. Specifically, the present disclosure relates to methods and systems for selectively and independently controlling the drive to both a pick roller and a feed roller of a document feeder system to protect against damage to or the misfeeding of documents.

BACKGROUND

It is well known in the art of imaging/printing equipment to use a document feeder system to support a stack of documents, and to feed these documents to the imaging/printing equipment, one at a time from the stack. Such document feeder systems typically include a feeder tray for supporting the stack of documents, and a skimmer apparatus for separating the documents in the stack from one another as they are transported into the imaging/printing equipment, one at a time from the top of the stack. The skimmer apparatus typically includes a pick roller, a feed roller, and a separator or retard roller located under the feed roller. In operation, the pick roller propels the top sheet of the stack to the feed roller, which then feeds the sheet to the transport rollers inside the imaging equipment, while the retard roller prevents (or attempts to prevent) multiple sheets from being feed at the same time.

However, special problems with feeding the stack of documents can arise, for example, when it is attempted to feed sheets of a limited length, i.e., short sheets, to the imaging equipment. To address such a problem, U.S. Pat. No. 6,679,490 B2, issued to Pioquinto et al. on Jan. 20, 2004, and commonly assigned to the assignee of this application, discloses a pick roller with a clutch, wherein drive to the pick roller is disengaged at times by a clutch to prevent the sheet under the top sheet from being fed too soon, which can lead to paper jams, improper feeding, and/or damage to the sheets such as by folding or creasing, etc. The entire disclosure of U.S. Pat. No. 6,679,490 B2 is herein incorporated by reference.

Nonetheless, while U.S. Pat. No. 6,679,490 B2 adequately addresses the problems associated with the feeding of short sheets, special problems with feeding the stack of documents to the imaging equipment can still arise, for example, when it is attempted to feed sheets which are very thin or ultra-thin, such as ultra-thin sheets known as Chinese onion skin, especially at high speeds. The feeding of such sheets, especially at high speeds, often results in over-pushing (overfeeding) by the skimmer apparatus, which again can lead to paper jams, improper feeding such as multi-feeding, and/or damage to the sheets such as by folding or creasing, etc.

Accordingly, to address the above stated issues, a method and system for feeding thin or ultra-thin documents to select equipment, one at a time, in a smooth, efficient and continuous manner, especially at high speeds, to minimize or prevent overfeeding, misfeeding, damaging of the documents or creating paper jams is needed. The exemplary teachings herein fulfill such a need. It is desired that the methods and systems for providing the above benefits be applicable to any instances or applications wherein a document feeder system is required.

SUMMARY

The exemplary technique(s), system(s) and method(s) presented herein relate to a feed roller system for high speed image scanning equipment, which improves feeding of documents, and in particular, thin or ultra-thin documents. The exemplary method and system include feeding documents or sheets sequentially from a stack via a pick roller and a feed roller, wherein drive to both the pick roller and the feed roller are independently and selectively controlled via dual clutches.

The pick roller and the feed roller of the present disclosure are driven by the same drive motor, however, each roller is associated with its own clutch, allowing the pick roller and feed roller to be selectively driven together, driven independently, and/or not driven at all. The clutches are electromechanical clutches, which when energized are used to drive the pick roller and feed roller, respectively, and when de-energized cut off drive to the pick roller and feed roller, respectively.

Initially, when feeding a document, the clutches are energized, and both rollers are driven. Drive to the pick roller is disabled by the pick roller clutch when the leading edge of the top document reaches a gap control sensor, downstream of the rollers, at which time the pick roller clutch is de-energized. Drive to the feed roller continues until it is disabled by the feed roller clutch when the leading edge of the top document reaches a page entry sensor, downstream of the gap control sensor and the first transport rollers, at which time the feed roller clutch is de-energized. The document is now driven only by the transport rollers, and overfeeding or pushing by the pick roller and/or feed roller is prevented. When the trailing edge of the document passes the gap control sensor, both clutches are re-energized, and drive to both the pick roller and the feed roller is re-established to commence feeding of the next document.

Additional objects, advantages and novel features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the drawing figures, like reference numerals refer to the same or similar elements.

FIG. 1 is an exemplary side view depiction of a transport system of a scanner having the exemplary feed roller system with dual clutch;

FIG. 2 a is an enlarged side view depiction of the feed roller system with dual clutch of the exemplary scanner of FIG. 1;

FIG. 2 b is an enlarged side view depiction of an alternate embodiment of the feed roller system;

FIG. 3 is a flow chart illustrating the operation of the feed roller system with dual clutch of the exemplary scanner of FIG. 1; and

FIG. 4 is a top view depiction of the feed roller system of FIG. 2a.

DETAILED DESCRIPTION

The following description refers to numerous specific details which are set forth by way of examples to provide a thorough understanding of the relevant teachings. It should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. It will be appreciated by those versed in the art that the exemplary teachings described herein enable the selective and independent driving of the feed roller system using the dual clutches, allowing for improved feeding of documents, especially thin or ultra-thin documents. The description now proceeds with a discussion of FIGS. 1-4, which depict by way of example the following: a side view of the overall transport system of an exemplary scanner device, a side view of its preferred feed roller system, a side view of an alternate feed roller system, a flow chart of the operation of the preferred feed roller system and a top view of the preferred feed roller system, respectively.

The exemplary scanner device and its transport system 100 of FIG. I are comprised of various functional components for facilitating and/or enabling its multitude of operating features. Entry into the transport system 100 of the scanner, wherein the various scanning functions are performed upon the document, is facilitated by usage of a document feeder or feed roller system 110 and a document feeder tray table 120 for supporting multiple pages or sheets of a document or stack of documents underneath the document feeder 110. At the other end of the transport system 100 is an exit tray 130 for storing accumulated documents upon full transport through the scanner transport system 100. In between the feed roller system 110 and the exit tray 130 are a plurality of transport rollers 140 which transport the documents along a transport path 150 through the scanner device.

The feed roller system 110 comprises a pick roller 112, a feed roller 114, and a separator or retard roller 116. The pick 112 and feed 114 rollers in the feed roller system 110 are preferably driven by the same motor, skimmer drive 118, although a plurality of motors can be used as described below. The feed roller system 110 delivers a document from the feeder tray 120 into the transport path 150 to the transport rollers 140 which are driven, at least in part, by a second motor, transport stage drive 148. The pick roller 112 pushes the top document from the feeder tray 120 into the scanner's entry/separation nip formed by the feed roller 114 and the separator/retard roller 116. The feed roller 114 then pushes the top document into the transport rollers 140, while the separator/retard roller 116 pushes any documents which may be under the top document backward or away from the nip to avoid feeding multiple documents into the transport path 150 at the same time.

The pick roller 112 and feed roller 114 are connected by a housing (not shown) as is known in the art, and are commonly referred to collectively as a skimmer. The skimmer pivots about feed roller 114, and thus can be in one of three angled positions, an up position, a down position and a generally horizontal feed position. All three positions are measured by the skimmer angle sensor 126.

Preferably, the skimmer drive 118 also drives at least the first pair of transport rollers 142. In the embodiment illustrated, the skimmer drive drives the first pair of transport rollers 142 and the second pair of transport rollers 144. In this embodiment, a main transport stage drive 148 drives the remaining transport rollers positioned along transport path 150.

When a stack of one or more documents is placed into the document feeder table/tray 120, the paper in feeder sensor (PIF) 122 detects the presence of the document, and activates the feeder table lift/drive 124 which in turn lifts the stack in the direction of document feeder 110 for input into the transport path 150. Upon receipt of a scan command, the document feeder 110 of the scanner moves the top page of the stack of documents, one at a time sequentially from the stack, using the skimmer drive 118, which drives the document feed roller system 110 to direct the top page downstream through the transport path 150 via transport rollers 140. The rollers 140 are regulated at least in part by main transport stage drive 148 (e.g., stepper motor), and are linked together via a transport belt, which also enables the pages of the stack of documents to be gripped for advancement down the transport path 150 appropriately, until they eventually reach the exit tray 130.

In order to prevent or minimize the potential for damaging the document being fed, drive to the pick roller 112 and the feed roller 114 is selectively controlled during the document feeding process by the document feed roller system 110. Drive to the pick roller 112 is selectively controlled by a pick roller clutch 113, and drive to the feed roller 114 is selectively controlled by a feed roller clutch 115. Each of the clutches 113 and 115 are controllable responsive to an associated sensor 117 and 119, respectively, as discussed in more detail below.

Turning now to FIG. 2 a, a stack of sheets or documents 200 is shown being fed by the document feed roller system 110 to the transport rollers 140. When it is desired to feed one or more sheets from the stack of sheets 200, the feeder tray table 120 is raised to lift the stack of documents 200 into contact with the skimmer, and thereby lifting the skimmer from its down position to its generally horizontal feed position shown in FIG. 2 a. When the skimmer angle sensor 126 senses that the skimmer is in its generally horizontal feed position, the skimmer drive 118 is started, and the pick roller 112 and feed roller 114 are rotated, as the respective clutches 113 and 115 are initially engaged.

As the pick roller 112 rotates, it propels the first sheet 210 towards feed roller 114. When sheet 210 reaches the entry/separation nip formed by the feed roller 114 and the separator/retard roller 116, the feed roller 114 propels the sheet 210 through the transport path into the imaging equipment. A sensor 117 is suitably located a short distance downstream of feed roller 114. When the leading edge 220 of sheet 210 reaches sensor 117 and is sensed thereby, the sensor 117 sends a signal to the electromechanical clutch 113 to de-energize, thus disengaging drive to the pick roller 112 to stop rotation of the pick roller 112, thereby preventing overfeeding or over pushing by the pick roller 112. The feed roller 114 continues to rotate and to propel the sheet 210 to the transport rollers 140.

When sheet 210 reaches the first pair of transport rollers 142, the first pair of transport rollers 142 propels the sheets 210 farther into the transport path 150 and towards the second pair of transport rollers 144 and subsequent pairs of transport rollers. A sensor 119 is suitably located a short distance downstream of first pair of transport rollers 142. When the leading edge 220 of sheet 210 reaches sensor 119 and is sensed thereby, the sensor 119 sends a signal to the electro-mechanical clutch 115 to de-energize, thus disengaging drive to the feed roller 114 to stop rotation of the feed roller 114, thereby preventing overfeeding or over pushing by the feed roller 114. The first pair of transport rollers 142 continues to rotate and to propel the sheet 210 to the second pair of transport rollers 144.

At this point in time, only the transport rollers 140 are propelling the sheet 210 further along the transport path 150. When the trailing edge 230 of sheet 210 clears or passes the sensor 117, the electromechanical clutches 113 and 115 are re-energized to once again start rotation of pick roller 112 and the feed roller 114 to feed the next sheet 211.

Accordingly, clutching both the pick roller and the feed roller allows independent control of the pick roller and feed roller and thus avoids the problem of over-pushing (overfeeding) and stressing documents in the nip, especially short and thin documents or thin documents of different lengths. Full advantage is seen on Chinese ultra-thin documents with less multi-feeds and less feeder jams.

FIG. 2 b illustrates an alternate embodiment of the feeder system 110, wherein drive to the pick roller 112 and to the feed roller 114 is accomplished with two motors 118 a and 118 b, respectively, instead of the single motor 118 of FIG. 2 a. Operation of the feeder system 110 is otherwise unchanged and remains as described with respect to FIG. 2 a.

Referring now to FIG. 3, the operation of the feeder system 110 is illustrated and described in flow chart form. At step 300, a stack of documents or sheets to be fed are loaded onto the document feeder tray table 120. To do so, the skimmer is typically lifted to its up position, and sensor 126 signals drive 118 to shut off. When the skimmer is lowered to its down position, sensor 126 signals feeder tray lift drive 124 to turn on, thereby raising the feeder tray table 120 and lifting the stack of documents into the skimmer. The skimmer is pushed up by the rising stack until is reaches its generally horizontal feed position, at which time sensor 126 signals drive 118 to turn on. At this time, the clutches 113 and 115 are engaged, and the pick roller 112 and feed roller 114 start to rotate (step 305).

Rollers 112 and/or 114 feed the top sheet 210 until the leading edge 220 is detected by sensor 117 (step 310). Sensor 117 then signals clutch 113 to disengage to stop the drive to the pick roller 112 and allow it to free wheel (step 315). Feed roller 114 continues to advance the sheet 210 until the leading edge 220 is detected by the page entry sensor 119 (step 320). Sensor 119 then signal clutch 115 to disengage to stop the drive to the feed roller 114 and allow it to free wheel (step 325). At this time, the first transport roller pair 142 continues to advance the sheet 210 into and along the transport path 150. When the trailing edge 230 is detected by (clears) sensor 117 (step 330), sensor 117 signals clutches 113 and 115 to re-engage to feed the next sheet 211 (step 305) so long as the paper in feeder (PIF) sensor 122 detects the presence of additional documents in the feeder tray table 120 (step 340). If sensor 122 does not detect the presence of additional documents, the feeder system 110 is stopped (step 345).

Turning now to FIG. 4, a top view of the rollers and sensors of FIG. 2 a is shown, illustrating the relative positioning there between. The paper in feeder (PIF) sensor 122 can be seen in front of the pick roller 112 (referencing from the bottom of FIG. 4 to the top of FIG. 4). The feed roller 114 is positioned after the pick roller 112. The separator roller 116 is located under the feed roller 114. Sensor 117, referred to as a gap control sensor, is located after the feed roller 116, but before the first pair of transport rollers 142. Sensor 119, preferably comprising a plurality of sensors (three shown), referred to as page entry sensors, is located after the first pair of transport rollers 142, but before the second pair of transport rollers 144. Various other sensors are shown between the first pair of transport rollers 142 and the second pair of transport rollers 144 to control various other scanner functions.

While the foregoing discussion presents the teachings in an exemplary fashion with respect to a conventional scanner device, it will be apparent to those skilled in the art that the teachings may apply to any type of device that employs an automated document feeding system (e.g., fax machine, industrial scanner, printer, or a combined printer/scanner/fax machine). Further, while the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. 

1. A sheet feeder apparatus, comprising: a pick roller for advancing a document from a stack; a feed roller for feeding the document; and a drive system for selectively driving the pick roller and the feed roller, wherein the drive system is adapted to selectively drive the feed roller and the pick roller together, to selectively drive the feed roller independent of the pick roller, and to selectively disengage drive to both the feed roller and the pick roller.
 2. The apparatus of claim 1, wherein the drive system comprises a first clutch for selectively disengaging drive to the pick roller.
 3. The apparatus of claim 2, wherein the first clutch is operable responsive to a first sensor which senses the document.
 4. The apparatus of claim 3, wherein the drive system comprises a second clutch for selectively disengaging drive to the feed roller.
 5. The apparatus of claim 4, wherein the second clutch is operable responsive to a second sensor which senses the document.
 6. The apparatus of claim 5, further comprising a pair of transport rollers.
 7. The apparatus of claim 5, wherein at least one motor selectively drives the pick roller and the feed roller.
 8. The apparatus of claim 6, wherein at least one motor selectively drives the pick roller, the feed roller and the pair of transport rollers.
 9. An apparatus for feeding documents from a stack of documents to a pair of transport rollers, each of the documents having a leading edge, the apparatus comprising: a pick roller; a feed roller downstream of the pick roller; a first sensor downstream of the feed roller for sensing the documents; and a second sensor downstream of the pair of transport rollers; the pick roller and the feed roller adapted to be driven together wherein the pick roller advances a first document towards the feed roller and the feed roller advances the first document to the first sensor; wherein when the leading edge of the first document reaches the first sensor, drive to the pick roller is halted, and when the leading edge of the first document reaches the second sensor, drive to the feed roller is halted.
 10. A method for feeding documents from a stack of documents, each of said documents having a leading edge, said method comprising the steps of: aligning a pick roller, a feed roller downstream of the pick roller, and a first sensor downstream of the feed roller, and a second sensor downstream of the first sensor; driving the pick roller and the feed roller together; advancing a first document from the pick roller to the feed roller; advancing the first document from the feed roller to the first sensor and sensing the first document via the first sensor; disengaging drive to the pick roller while the first document is being sensed by the first sensor; advancing the first document to the second sensor and sensing the first document via the second sensor; and disengaging drive to the feed roller while the first document is being sensed by the first sensor.
 11. The method of claim 10, further comprising the step of re-engaging drive to the pick roller and the feed roller to advance a second document after the first document clears the first sensor.
 12. (canceled)
 13. A sheet feeder apparatus for feeding documents to document transport roller of a device, comprising: a pick roller for advancing a document from a stack; a feed roller proximate the pick roller for feeding the document into the document transport path; and a drive system for driving the pick roller and the feed roller, the drive system includes a first clutch for selectively disengaging drive to the pick roller, and a second clutch for selectively disengaging drive to the feed roller; wherein the drive system is adapted to selectively drive the feed roller and the pick roller together, to selectively drive the feed roller independent of the pick roller, and to selectively disengage drive to both the feed roller and the pick roller.
 14. A method for feeding documents from a stack of documents to a document transport roller of a device, each of the documents having a leading edge, the method comprising the steps of: driving a pick roller and a feed roller together; advancing a first document from the pick roller to the feed roller; advancing the first document from the feed roller to a first sensor and sensing the first document via the first sensor; disengaging drive to the pick roller when the first document is sensed by the first sensor; advancing the first document to a second sensor and sensing the first document via the second sensor; and disengaging drive to the feed roller when the first document is sensed by the second sensor.
 15. The method of claim 14, further comprising the step of re-engaging drive to the pick roller and the feed roller to advance a second document after the first document clears the first sensor.
 16. (canceled) 